[thirdparty/glibc.git] / sysdeps / powerpc / powerpc64 / power7 / strrchr.S

/* Optimized strrchr implementation for PowerPC64/POWER7 using cmpb insn.
   Copyright (C) 2014-2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <sysdep.h>

/* int [r3] strrchr (char *s [r3], int c [r4])  */
	.machine  power7
ENTRY (strrchr)
	CALL_MCOUNT 2
	dcbt	0,r3
	clrrdi	r8,r3,3	      /* Align the address to doubleword boundary.  */
	cmpdi	cr7,r4,0
	ld	r12,0(r8)     /* Load doubleword from memory.  */
	li	r9,0	      /* used to store last occurence */
	li	r0,0	      /* Doubleword with null chars to use
				 with cmpb.  */

	rlwinm	r6,r3,3,26,28 /* Calculate padding.  */

	beq	cr7,L(null_match)

	/* Replicate byte to doubleword.  */
	insrdi	r4,r4,8,48
	insrdi	r4,r4,16,32
	insrdi	r4,r4,32,0

	/* r4 is changed now ,if its passed as more chars
	   check for null again */
	cmpdi	cr7,r4,0
	beq	cr7,L(null_match)
	/* Now r4 has a doubleword of c bytes and r0 has
	   a doubleword of null bytes.  */

	cmpb	r10,r12,r4     /* Compare each byte against c byte.  */
	cmpb	r11,r12,r0     /* Compare each byte against null byte.  */

	/* Move the doublewords left and right to discard the bits that are
	   not part of the string and bring them back as zeros.  */
#ifdef __LITTLE_ENDIAN__
	srd	r10,r10,r6
	srd	r11,r11,r6
	sld	r10,r10,r6
	sld	r11,r11,r6
#else
	sld	r10,r10,r6
	sld	r11,r11,r6
	srd	r10,r10,r6
	srd	r11,r11,r6
#endif
	or	r5,r10,r11    /* OR the results to speed things up.  */
	cmpdi	cr7,r5,0      /* If r5 == 0, no c or null bytes
				 have been found.  */
	bne	cr7,L(done)

L(align):
	mtcrf	0x01,r8

	/* Are we now aligned to a doubleword boundary?  If so, skip to
	   the main loop.  Otherwise, go through the alignment code.  */

	bt	28,L(loop)

	/* Handle WORD2 of pair.  */
	ldu	r12,8(r8)
	cmpb	r10,r12,r4
	cmpb	r11,r12,r0
	or	r5,r10,r11
	cmpdi	cr7,r5,0
	bne	cr7,L(done)
	b	L(loop)	      /* We branch here (rather than falling through)
				 to skip the nops due to heavy alignment
				 of the loop below.  */
	.p2align  5
L(loop):
	/* Load two doublewords, compare and merge in a
	   single register for speed.  This is an attempt
	   to speed up the null-checking process for bigger strings.  */
	ld	r12,8(r8)
	ldu	r7,16(r8)
	cmpb	r10,r12,r4
	cmpb	r11,r12,r0
	cmpb	r6,r7,r4
	cmpb	r7,r7,r0
	or	r12,r10,r11
	or	r5,r6,r7
	or	r5,r12,r5
	cmpdi	cr7,r5,0
	beq	cr7,L(loop)

	/* OK, one (or both) of the doublewords contains a c/null byte.  Check
	   the first doubleword and decrement the address in case the first
	   doubleword really contains a c/null byte.  */
	cmpdi	cr6,r12,0
	addi	r8,r8,-8
	bne	cr6,L(done)

	/* The c/null byte must be in the second doubleword.  Adjust the
	   address again and move the result of cmpb to r10 so we can calculate
	   the pointer.  */

	mr	r10,r6
	mr	r11,r7
	addi	r8,r8,8

	/* r10/r11 have the output of the cmpb instructions, that is,
	   0xff in the same position as the c/null byte in the original
	   doubleword from the string.  Use that to calculate the pointer.  */

L(done):
	/* if there are more than one 0xff in r11, find the first pos of ff
	   in r11 and fill r10 with 0 from that position */
	cmpdi	cr7,r11,0
	beq	cr7,L(no_null)
#ifdef __LITTLE_ENDIAN__
	addi	r3,r11,-1
	andc	r3,r3,r11
	popcntd r0,r3
#else
	cntlzd	r0,r11
#endif
	subfic	r0,r0,63
	li	r6,-1
#ifdef __LITTLE_ENDIAN__
	srd	r0,r6,r0
#else
	sld	r0,r6,r0
#endif
	and	r10,r0,r10
L(no_null):
#ifdef __LITTLE_ENDIAN__
	cntlzd	r0,r10		/* Count leading zeros before c matches.  */
	addi	r3,r10,-1
	andc	r3,r3,r10
	addi	r10,r11,-1
	andc	r10,r10,r11
	cmpld	cr7,r3,r10
	bgt	cr7,L(no_match)
#else
	addi	r3,r10,-1	/* Count trailing zeros before c matches.  */
	andc	r3,r3,r10
	popcntd	r0,r3
	cmpld	cr7,r11,r10
	bgt	cr7,L(no_match)
#endif
	srdi	r0,r0,3		/* Convert trailing zeros to bytes.  */
	subfic	r0,r0,7
	add	r9,r8,r0      /* Return address of the matching c byte
				 or null in case c was not found.  */
	li	r0,0
	cmpdi	cr7,r11,0     /* If r11 == 0, no null's have been found.  */
	beq	cr7,L(align)

	.align	4
L(no_match):
	mr	r3,r9
	blr

/* We are here because strrchr was called with a null byte.  */
	.align	4
L(null_match):
	/* r0 has a doubleword of null bytes.  */

	cmpb	r5,r12,r0     /* Compare each byte against null bytes.  */

	/* Move the doublewords left and right to discard the bits that are
	   not part of the string and bring them back as zeros.  */
#ifdef __LITTLE_ENDIAN__
	srd	r5,r5,r6
	sld	r5,r5,r6
#else
	sld	r5,r5,r6
	srd	r5,r5,r6
#endif
	cmpdi	cr7,r5,0      /* If r10 == 0, no c or null bytes
				 have been found.  */
	bne	cr7,L(done_null)

	mtcrf	0x01,r8

	/* Are we now aligned to a quadword boundary?  If so, skip to
	   the main loop.  Otherwise, go through the alignment code.  */

	bt	28,L(loop_null)

	/* Handle WORD2 of pair.  */
	ldu	r12,8(r8)
	cmpb	r5,r12,r0
	cmpdi	cr7,r5,0
	bne	cr7,L(done_null)
	b	L(loop_null)  /* We branch here (rather than falling through)
				 to skip the nops due to heavy alignment
				 of the loop below.  */

	/* Main loop to look for the end of the string.  Since it's a
	   small loop (< 8 instructions), align it to 32-bytes.  */
	.p2align  5
L(loop_null):
	/* Load two doublewords, compare and merge in a
	   single register for speed.  This is an attempt
	   to speed up the null-checking process for bigger strings.  */
	ld	r12,8(r8)
	ldu	r11,16(r8)
	cmpb	r5,r12,r0
	cmpb	r10,r11,r0
	or	r6,r5,r10
	cmpdi	cr7,r6,0
	beq	cr7,L(loop_null)

	/* OK, one (or both) of the doublewords contains a null byte.  Check
	   the first doubleword and decrement the address in case the first
	   doubleword really contains a null byte.  */

	cmpdi	cr6,r5,0
	addi	r8,r8,-8
	bne	cr6,L(done_null)

	/* The null byte must be in the second doubleword.  Adjust the address
	   again and move the result of cmpb to r10 so we can calculate the
	   pointer.  */

	mr	r5,r10
	addi	r8,r8,8

	/* r5 has the output of the cmpb instruction, that is, it contains
	   0xff in the same position as the null byte in the original
	   doubleword from the string.  Use that to calculate the pointer.  */
L(done_null):
#ifdef __LITTLE_ENDIAN__
	addi	r0,r5,-1
	andc	r0,r0,r5
	popcntd	r0,r0
#else
	cntlzd	r0,r5	      /* Count leading zeros before the match.  */
#endif
	srdi	r0,r0,3	      /* Convert trailing zeros to bytes.  */
	add	r3,r8,r0      /* Return address of the matching null byte.  */
	blr
END (strrchr)
weak_alias (strrchr, rindex)
libc_hidden_builtin_def (strrchr)
Commit	Line	Data
c7debbdf	1	/* Optimized strrchr implementation for PowerPC64/POWER7 using cmpb insn.
f7a9f785	2	Copyright (C) 2014-2016 Free Software Foundation, Inc.
c7debbdf RS	3	This file is part of the GNU C Library.
	4
	5	The GNU C Library is free software; you can redistribute it and/or
	6	modify it under the terms of the GNU Lesser General Public
	7	License as published by the Free Software Foundation; either
	8	version 2.1 of the License, or (at your option) any later version.
	9
	10	The GNU C Library is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	13	Lesser General Public License for more details.
	14
	15	You should have received a copy of the GNU Lesser General Public
	16	License along with the GNU C Library; if not, see
	17	<http://www.gnu.org/licenses/>. */
	18
	19	#include <sysdep.h>
	20
	21	/* int [r3] strrchr (char s [r3], int c [r4]) /
	22	.machine power7
	23	ENTRY (strrchr)
	24	CALL_MCOUNT 2
	25	dcbt 0,r3
	26	clrrdi r8,r3,3 /* Align the address to doubleword boundary. */
	27	cmpdi cr7,r4,0
	28	ld r12,0(r8) /* Load doubleword from memory. */
	29	li r9,0 /* used to store last occurence */
	30	li r0,0 /* Doubleword with null chars to use
	31	with cmpb. */
	32
	33	rlwinm r6,r3,3,26,28 /* Calculate padding. */
	34
	35	beq cr7,L(null_match)
	36
	37	/* Replicate byte to doubleword. */
	38	insrdi r4,r4,8,48
	39	insrdi r4,r4,16,32
	40	insrdi r4,r4,32,0
	41
	42	/* r4 is changed now ,if its passed as more chars
	43	check for null again */
	44	cmpdi cr7,r4,0
	45	beq cr7,L(null_match)
	46	/* Now r4 has a doubleword of c bytes and r0 has
	47	a doubleword of null bytes. */
	48
	49	cmpb r10,r12,r4 /* Compare each byte against c byte. */
	50	cmpb r11,r12,r0 /* Compare each byte against null byte. */
	51
	52	/* Move the doublewords left and right to discard the bits that are
	53	not part of the string and bring them back as zeros. */
	54	#ifdef __LITTLE_ENDIAN__
	55	srd r10,r10,r6
	56	srd r11,r11,r6
	57	sld r10,r10,r6
	58	sld r11,r11,r6
	59	#else
	60	sld r10,r10,r6
	61	sld r11,r11,r6
	62	srd r10,r10,r6
	63	srd r11,r11,r6
	64	#endif
	65	or r5,r10,r11 /* OR the results to speed things up. */
	66	cmpdi cr7,r5,0 /* If r5 == 0, no c or null bytes
67	have been found. */
68	bne cr7,L(done)
69
70	L(align):
71	mtcrf 0x01,r8
72
73	/* Are we now aligned to a doubleword boundary? If so, skip to
74	the main loop. Otherwise, go through the alignment code. */
75
76	bt 28,L(loop)
77
78	/* Handle WORD2 of pair. */
79	ldu r12,8(r8)
80	cmpb r10,r12,r4
81	cmpb r11,r12,r0
82	or r5,r10,r11
83	cmpdi cr7,r5,0
84	bne cr7,L(done)
85	b L(loop) /* We branch here (rather than falling through)
86	to skip the nops due to heavy alignment
87	of the loop below. */
88	.p2align 5
89	L(loop):
90	/* Load two doublewords, compare and merge in a
91	single register for speed. This is an attempt
92	to speed up the null-checking process for bigger strings. */
93	ld r12,8(r8)
94	ldu r7,16(r8)
95	cmpb r10,r12,r4
96	cmpb r11,r12,r0
97	cmpb r6,r7,r4
98	cmpb r7,r7,r0
99	or r12,r10,r11
100	or r5,r6,r7
101	or r5,r12,r5
102	cmpdi cr7,r5,0
103	beq cr7,L(loop)
104
105	/* OK, one (or both) of the doublewords contains a c/null byte. Check
106	the first doubleword and decrement the address in case the first
107	doubleword really contains a c/null byte. */
108	cmpdi cr6,r12,0
109	addi r8,r8,-8
110	bne cr6,L(done)
111
112	/* The c/null byte must be in the second doubleword. Adjust the
113	address again and move the result of cmpb to r10 so we can calculate
114	the pointer. */
115
116	mr r10,r6
117	mr r11,r7
118	addi r8,r8,8
119
120	/* r10/r11 have the output of the cmpb instructions, that is,
121	0xff in the same position as the c/null byte in the original
122	doubleword from the string. Use that to calculate the pointer. */
123
124	L(done):
125	/* if there are more than one 0xff in r11, find the first pos of ff
126	in r11 and fill r10 with 0 from that position */
127	cmpdi cr7,r11,0
128	beq cr7,L(no_null)
129	#ifdef __LITTLE_ENDIAN__
130	addi r3,r11,-1
131	andc r3,r3,r11
132	popcntd r0,r3
133	#else
134	cntlzd r0,r11
135	#endif
136	subfic r0,r0,63
137	li r6,-1
138	#ifdef __LITTLE_ENDIAN__
139	srd r0,r6,r0
140	#else
141	sld r0,r6,r0
142	#endif
143	and r10,r0,r10
144	L(no_null):
145	#ifdef __LITTLE_ENDIAN__
146	cntlzd r0,r10 /* Count leading zeros before c matches. */
147	addi r3,r10,-1
148	andc r3,r3,r10
149	addi r10,r11,-1
150	andc r10,r10,r11
151	cmpld cr7,r3,r10
152	bgt cr7,L(no_match)
153	#else
154	addi r3,r10,-1 /* Count trailing zeros before c matches. */
155	andc r3,r3,r10
156	popcntd r0,r3
157	cmpld cr7,r11,r10
158	bgt cr7,L(no_match)
159	#endif
160	srdi r0,r0,3 /* Convert trailing zeros to bytes. */
161	subfic r0,r0,7
162	add r9,r8,r0 /* Return address of the matching c byte
163	or null in case c was not found. */
164	li r0,0
165	cmpdi cr7,r11,0 /* If r11 == 0, no null's have been found. */
166	beq cr7,L(align)
167
168	.align 4
169	L(no_match):
170	mr r3,r9
171	blr
172
173	/* We are here because strrchr was called with a null byte. */
174	.align 4
175	L(null_match):
176	/* r0 has a doubleword of null bytes. */
177
178	cmpb r5,r12,r0 /* Compare each byte against null bytes. */
179
180	/* Move the doublewords left and right to discard the bits that are
181	not part of the string and bring them back as zeros. */
182	#ifdef __LITTLE_ENDIAN__
183	srd r5,r5,r6
184	sld r5,r5,r6
185	#else
186	sld r5,r5,r6
187	srd r5,r5,r6
188	#endif
189	cmpdi cr7,r5,0 /* If r10 == 0, no c or null bytes
190	have been found. */
191	bne cr7,L(done_null)
192
193	mtcrf 0x01,r8
194
195	/* Are we now aligned to a quadword boundary? If so, skip to
196	the main loop. Otherwise, go through the alignment code. */
197
198	bt 28,L(loop_null)
199
200	/* Handle WORD2 of pair. */
201	ldu r12,8(r8)
202	cmpb r5,r12,r0
203	cmpdi cr7,r5,0
204	bne cr7,L(done_null)
205	b L(loop_null) /* We branch here (rather than falling through)
206	to skip the nops due to heavy alignment
207	of the loop below. */
208
209	/* Main loop to look for the end of the string. Since it's a
210	small loop (< 8 instructions), align it to 32-bytes. */
211	.p2align 5
212	L(loop_null):
213	/* Load two doublewords, compare and merge in a
214	single register for speed. This is an attempt
215	to speed up the null-checking process for bigger strings. */
216	ld r12,8(r8)
217	ldu r11,16(r8)
218	cmpb r5,r12,r0
219	cmpb r10,r11,r0
220	or r6,r5,r10
221	cmpdi cr7,r6,0
222	beq cr7,L(loop_null)
223
224	/* OK, one (or both) of the doublewords contains a null byte. Check
225	the first doubleword and decrement the address in case the first
226	doubleword really contains a null byte. */
227
228	cmpdi cr6,r5,0
229	addi r8,r8,-8
230	bne cr6,L(done_null)
231
232	/* The null byte must be in the second doubleword. Adjust the address
233	again and move the result of cmpb to r10 so we can calculate the
234	pointer. */
235
236	mr r5,r10
237	addi r8,r8,8
238
239	/* r5 has the output of the cmpb instruction, that is, it contains
240	0xff in the same position as the null byte in the original
241	doubleword from the string. Use that to calculate the pointer. */
242	L(done_null):
243	#ifdef __LITTLE_ENDIAN__
244	addi r0,r5,-1
245	andc r0,r0,r5
246	popcntd r0,r0
247	#else
248	cntlzd r0,r5 /* Count leading zeros before the match. */
249	#endif
250	srdi r0,r0,3 /* Convert trailing zeros to bytes. */
251	add r3,r8,r0 /* Return address of the matching null byte. */
252	blr
253	END (strrchr)
254	weak_alias (strrchr, rindex)
255	libc_hidden_builtin_def (strrchr)